DIY solar dehumidifier - Page 2

jeff5may · 11-07-13, 11:37 AM

Some manufacturers are incorporating this method of dehumidification into their heat recovery ventilators and air handlers.

They call it a dessicant wheel or an enthalpy wheel or a thermal wheel.

These guys have made a Rube Goldberg-esque machine that claims to do what you are after:

http://www.advantixsystems.com/pdf/H...s_Brochure.pdf

It looks almost like an ammonia refrigeration system to me!

Boz86 · 11-07-13, 12:38 PM

They got a patent I looked at before, but here's the general article on U of MD's project.

Oops, just found out I'm still too new to post links, but if you'll search google news for
'university of maryland solar dehumidifier' it's the only link that pops up.

They did exactly what you're talking about.

http://2007.solarteam.org/page.php?id=641

Daox · 11-07-13, 12:49 PM

I googled it and added the link for you.

Daox · 11-07-13, 01:08 PM

I just did a little googling myself. Here is an interesting solar dehumidifier. I think they call it "solar" but in order to make it solar you'd have to have solar hot water. The hot water is used to regenerate the descicant. Their PDF manual has a lot of info on the unit.

Solar Dehumidifier

Quote:

HOW IT WORKS
The DH3000 effectively removes moisture at normal temperatures without the freeze-up
problems inherent with refrigerant dehumidifiers and/or conventional air conditioners. This
enables the unit to maintain lower relative humidity and to dry deeper, thereby having a
more significant effect on carpets, floors, walls, contents, and structural materials. This
capability also inhibits mold and mildew growth caused by moist or humid conditions.

The “heart” of the DH3000 is the desiccant wheel (see wheel specs). The detail in Fig. 1
shows that the wheel is made with a series of air passages or channels. Air can be forced
through these channels in either direction.

Figure 1
The desiccant wheel is made entirely of a desiccant/fiber material. Desiccants are
extraordinary substances, having a high capacity for moisture adsorption, while being
easily regenerated. When damp air passes through the desiccant wheel, it adsorbs the
moisture into the desiccant material within the wheel and dries the air. Conversely, when
desiccants are heated (also called regeneration), they release the moisture and become
regenerated.

The DH3000 utilizes two air streams through the wheel to complete this cycle: the Process
Air Stream and the Regeneration Air Stream. Again, Figure 1 illustrates how the cycle
works.

In the Process Air Stream, damp air is drawn through the channels in the wheel where the
desiccant absorbs most of the moisture in the air. This air, now “dried out”, is then
supplied back into the area being dehumidified. As the DH3000 operates, the wheel turns
very slowly so that a new portion of it is always in the drying zone.
The Regeneration Air Stream is heated by the hot water coil and forced through the wheel 8
at the drying zone. This hot air now causes the desiccants to release the moisture in a
vapor form. The moisture is exhausted through the Regeneration Air Outlet. This moist
air, also called “Exhaust Air”, is then vented to the outside. At this point, the wheel has
been reactivated and the dehumidification cycle is complete.

The Regeneration Air Stream should always be vented to the outside. Process Air Supply
may be discharged directly back into the space or ducted to the supply of the air
conditioner.

Review of the process:
• Dry air or process air is returned to the room or to the area being dehumidified.
• As the wheel turns; the “wet” area rotates through the drying zone and is exposed to
the heated regeneration air stream.
• Moisture in the desiccant is released into the regeneration air stream.
• The regeneration air, with the moisture, is vented to the outside.

peacmar · 11-07-13, 02:46 PM

Now, the question remains....
How do I build it myself and how am I going to fit it in my little farm house....?

Daox · 11-07-13, 02:58 PM

It would probably be easier to build outside and duct into the house.

peacmar · 11-07-13, 07:22 PM

Quote:

Originally Posted by Daox

It would probably be easier to build outside and duct into the house.

Sorry I wasn't being serious with that statement. Most certainly would fit better outside, one thing I am honestly curious about is the cost effectiveness of such a unit. I could build one, I have access to all the equipment that I don't have at home to do so. But what would the pay off be in what amount of time. My goal is to be independent of the grid, so I tend to lean more towards the simpler ideas that can be constructed from easily accessible parts and uses the least amount of energy possible.

jeff5may · 11-08-13, 07:51 AM

Peacmar,

It really depends on your dehumidification needs and available resources. It should be fairly simple to run a liquid loop like the university did. Rig up a swamp cooler indoors and fill it with salt. When the salt hydrates, run the fluid outdoors to a solar regenerator. Some sort of concentrator would work well with this type of setup, i.e. evacuated tube collector or parabolic trough. It would generate the high temperatures one would need to evaporate or boil the water out of the salt.

peacmar · 11-08-13, 08:52 AM

The funny thing is that I joined this thread for curiosity sake, but am now seriously considering such a contraption. Part of my foundation is over 100 years old and has a small stream that runs through my basement every spring so moisture is a large issue. Granted, I plan to replace the field stones one day but not any time soon. I also have an abundance of hot water at my disposal. I run an outdoor gasification burner year round to supply my family's hot water needs. We receive large amount of kiln dried scrap wood from local industry so I have an endless supply therefore it was an economical choice for us. That being said, I think I can utilise this heat source to regenerate the dessicant. Even if I have to manually switch out the media every so often it would be worth not running a 2500 watt dehumidifier 3-4 months a year. Last night while pondering this, I envisioned a resemblance to a swamp cooler also. Forced air to speed things up, a water overflow draining into the basement sump. I'm thinking about either interchangeable or refillable cartridges for ease. And material choice will be important also, especially if I use salt.

Now you guys have gone and done it..... yet one more project i have that was conceived on this wonderful website....

jeff5may · 11-08-13, 02:04 PM

Peacmar,

Here's an idea for you. Since you have a high-grade heat source, you could run a regenerator basically for free. Just run the dehumidifier as a traditional evap-pad cooler, which would dry the air with the brine solution. Either tap the pump outlet so that a percentage of the brine went through the regenerator and back into the sump, or gravity feed an overflow tube to the heat source where the hot brine could evaporate. As long as the heat source was active, the unit would move lots of water out of the airstream. If the air needs to be drier, just add more Damp-rid to the sump. At a certain point, you would never need to add more salt!

U CAN DU IT!

11-07-13, 11:37 AM	#11
jeff5may Supreme EcoRenovator Join Date: Jan 2010 Location: elizabethtown, ky, USA Posts: 2,431 Thanks: 431 Thanked 619 Times in 517 Posts	Some manufacturers are incorporating this method of dehumidification into their heat recovery ventilators and air handlers. They call it a dessicant wheel or an enthalpy wheel or a thermal wheel. These guys have made a Rube Goldberg-esque machine that claims to do what you are after: http://www.advantixsystems.com/pdf/H...s_Brochure.pdf It looks almost like an ammonia refrigeration system to me! Last edited by jeff5may; 11-08-13 at 07:41 AM.. Reason: words

11-07-13, 12:38 PM	#12
Boz86 Lurking Renovator Join Date: Oct 2013 Location: Maryland Posts: 6 Thanks: 0 Thanked 1 Time in 1 Post	They got a patent I looked at before, but here's the general article on U of MD's project. Oops, just found out I'm still too new to post links, but if you'll search google news for 'university of maryland solar dehumidifier' it's the only link that pops up. They did exactly what you're talking about. http://2007.solarteam.org/page.php?id=641 Last edited by Daox; 11-07-13 at 12:49 PM.. Reason: added link

11-07-13, 12:49 PM	#13
Daox Administrator Join Date: Aug 2008 Location: Germantown, WI Posts: 5,525 Thanks: 1,162 Thanked 374 Times in 305 Posts	I googled it and added the link for you. __________________ Current project - To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. & To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

11-07-13, 02:58 PM	#16
Daox Administrator Join Date: Aug 2008 Location: Germantown, WI Posts: 5,525 Thanks: 1,162 Thanked 374 Times in 305 Posts	It would probably be easier to build outside and duct into the house. __________________ Current project - To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. & To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

11-07-13, 02:46 PM	#15
peacmar Lurking Renovator Join Date: Jun 2011 Location: fond du lac, wi Posts: 26 Thanks: 0 Thanked 5 Times in 5 Posts	Now, the question remains.... How do I build it myself and how am I going to fit it in my little farm house....?

11-08-13, 07:51 AM	#18
jeff5may Supreme EcoRenovator Join Date: Jan 2010 Location: elizabethtown, ky, USA Posts: 2,431 Thanks: 431 Thanked 619 Times in 517 Posts	Peacmar, It really depends on your dehumidification needs and available resources. It should be fairly simple to run a liquid loop like the university did. Rig up a swamp cooler indoors and fill it with salt. When the salt hydrates, run the fluid outdoors to a solar regenerator. Some sort of concentrator would work well with this type of setup, i.e. evacuated tube collector or parabolic trough. It would generate the high temperatures one would need to evaporate or boil the water out of the salt.

11-08-13, 08:52 AM	#19
peacmar Lurking Renovator Join Date: Jun 2011 Location: fond du lac, wi Posts: 26 Thanks: 0 Thanked 5 Times in 5 Posts	The funny thing is that I joined this thread for curiosity sake, but am now seriously considering such a contraption. Part of my foundation is over 100 years old and has a small stream that runs through my basement every spring so moisture is a large issue. Granted, I plan to replace the field stones one day but not any time soon. I also have an abundance of hot water at my disposal. I run an outdoor gasification burner year round to supply my family's hot water needs. We receive large amount of kiln dried scrap wood from local industry so I have an endless supply therefore it was an economical choice for us. That being said, I think I can utilise this heat source to regenerate the dessicant. Even if I have to manually switch out the media every so often it would be worth not running a 2500 watt dehumidifier 3-4 months a year. Last night while pondering this, I envisioned a resemblance to a swamp cooler also. Forced air to speed things up, a water overflow draining into the basement sump. I'm thinking about either interchangeable or refillable cartridges for ease. And material choice will be important also, especially if I use salt. Now you guys have gone and done it..... yet one more project i have that was conceived on this wonderful website....

11-08-13, 02:04 PM	#20
jeff5may Supreme EcoRenovator Join Date: Jan 2010 Location: elizabethtown, ky, USA Posts: 2,431 Thanks: 431 Thanked 619 Times in 517 Posts	Peacmar, Here's an idea for you. Since you have a high-grade heat source, you could run a regenerator basically for free. Just run the dehumidifier as a traditional evap-pad cooler, which would dry the air with the brine solution. Either tap the pump outlet so that a percentage of the brine went through the regenerator and back into the sump, or gravity feed an overflow tube to the heat source where the hot brine could evaporate. As long as the heat source was active, the unit would move lots of water out of the airstream. If the air needs to be drier, just add more Damp-rid to the sump. At a certain point, you would never need to add more salt! U CAN DU IT!